Wheelband continuous casting machine having a single point band-tensioning device



Q 1 United States Patent [111 3,545,527

[72] Inventors Thomas L. Bray 2.749.584 6/ 1956 Fey et a1. 164/278 Birmingham, Alabama; 3,318,364 /1967 Bray et al l64/278X George C. Ward; Daniel B. Cofer, 3,318,367 5/1967 Bray 164/276 Carrollton, Georgia 3,336,972 8/1967 Cofer et a1. 164/278 1 [21] P 727887 Primary Examiner-J. Spencer Overholser [22] Wed May 1968 Assistant Examiner-R. Spencer Annear [45] patfamed 1970 Attorney-Jones and Thomas [73] Asslgnee Southwlre Company Carrollton, Georgia a corporation of Georgia N IN ASTING MACHINE [54] gfg ggg gg g ggtgfi ABSTRACT: The invention disclosed is a casting machine in- DEVICE cludmg a casting wheel with a peripheral groove, a band to 10 Claims, 4 Drawing Figs. close a portion of the groove and form aclosed casting mold, a plurality of band-support wheels to position the band relative [52] U.S.Cl. 164/154, to the casting wheel, and a band-tensioning device having a l64/278 wheel-supporting means which is for supporting a band-sup- 1 Int. Cl. port whee] through a ingle point and includes a posi- [50] Field of Search 164/87, timing means f positioning and urging the band suppon 154, 278 wheel against the band with a substantially constant resilient force applied through the single point. The positioning means [56] References Cited includes a resilient means for providing a resilient force and an UNITED STATES PATENTS adjusting means for maintaining the resilient force substanl,6 I 2,737 12/1926 Lane 164/278 tially constant in spite of changing operating conditions.

ULS-l PATENTEnnEc glam MENU 3.545.527-

' GEORGE c. WARD. DAN/EL B. COFER 5 v ATTORNEYS PATENIEDUEB 8l970 3545527 SHEET 3 BF 3 INVENTOR5= THoMAs L. BRAY 050m: c. WARD r DAN/EL 5. com? ATTORNEYS 1 WHEELBAND CONTINUOUS CASTING MACHINE HAVING A SINGLE POINT BAND-TENSIONING DEVICE BACKGROUND OF THE INVENTION 1. Field of the invention I This invention relates to continuous casting machines and more particularly, to a casting machine with a band-tensioning device which provides substantially constant resilient tension in a band that engages a rotating casting wheel.

2. Description of the Prior Art A casting machine with a band-tensioning device is well known in the art. Typical of such a casting machine is a casting machine having a casting wheel with a peripheral groove that is closed by a band and in which a band-tensioning device maintains tension in the band. i

The band-tensioning device generally includes a resilient spring to urge a band-support or band-tensioning wheel against the band with a resilient force that is sufficient to hold theband in tension. A difficulty with such a prior art band-tensioning device is that the resilient force frequently varies with changing operating conditions. I

For example, if tension in the band. starts to decreas because the band is lengthening-with an increase in its temperature, the resulting motion of the band-support wheel causes the resilient spring in a prior art band-tensioning device to increase in length. This, in turn, causes a decrease in the compression of the resilient spring and a corresponding decrease in the band tension which will be maintained by the resilient spring. Conversely, if tension in the band starts to increase because a piece of metal is forcing the band away from the casting wheel, the resulting motion of the band-support wheel causes the resilient spri'ng in a prior art band-tensioning device to decrease in length. This, in turn, causes an increase in the compression of the resilient spring and a corresponding increase in the band tension which will be maintained by the resilient spring.Thus, the band tension provided by the bandtensioning device in a prior art casting machine has characteristically varied with operating conditions so as to cause early fatigue and failure of the band and other operating difficulties.

SUMMARY OF THE INVENTION The above-mentioned and other difficulties associated with a prior art casting machine are substantially avoided by the invention disclosed hereimThis is because the invention is a casting machine with a band-tensioning device having a wheelsupporting means which is for supporting a band-supwport wheel and which includes a positioning means for posigle point being positioned so that twisting of the band-support wheel does not cause frictional resistance to that movement of the band-support wheel which is in response to the positioning means or otherwise necessary to maintain a substantially constant band tension. Furthermore, the invention provides a casting machine in which a force tending to cause an under undesired increase in band tension need not overcome the inertia of supporting and other structure in the casting machine before response of the positioning means may occur.

As generally indicated above, these improvements in a casting machine are provided by a casting machine having a bandtensioning device which includes a band-support wheel positioned to engage the band and mounted on a shaft for rotation about an'axis, and a wheel-supporting means which is for supporting the band-support wheel through a single point and which includes a positioning means for positioning and urging the band-supportwheel against the band with a substantially constant resilient force. The positioning means includes both a resilient means for providing a resilient force and an adjusting means for maintaining the resilient force substantially constant. In addition to the positioning means, the wheel-supporting means includes a carrying means for carrying the shaft on which the band-support wheel is mounted, and a guiding means for guidingthe carrying means along a line of motion transverse to the axis oftheband-support wheel.

The positioning means positions thecarrying means along the line of motion with a substantially constant resilient force applied through the single point. The single pointis displaced from the axis of the band-support wheel and is otherwise positioned relative to the guiding means so that neither the resilient force nor an opposing force resulting from an increase or decrease in band tension causes frictional resistance to motion of the carrying means relative to the guiding means.

DESCRIPTION THE DRAWING device in the casting machine shown in FIG. 1 taken in the line 2-2 ofFIG. l; V

FIG. 3 is a cross-sectional view of the band-tensioning device in the casting machine shown in FIG. 1 taken in the line 3-3 in FIG. 2; and t 3 FIG. 4 is a schematic diagram'showing an electrical circuit for the casting machine shownin FIG. 1.

, DESCRIPTION OF AN EMBODIMENT These FIGS. and the following detailed description disclose a specific embodiment of the invention. However, it will be understood that the invention is not limited to this specific embodiment since it may be embodied in other equivalent forms.

The invention disclosed herein is best understood as an otherwise conventional casting machine C having a band-tensioning device 11. Referring to FIG. 1, it will be see seen that the casting machine-C includesv a rotating casting wheel W with a peripheral groove (not shown) and an endless metal band B engaging a portion of the periphery of the casting wheel W toform, with the peripheral groove, a casting mold (not shown) into which molten metal passes from a pouring device P. The band B is positioned against the casting wheel W by a plurality of support wheels S.

The tensioning device 11 is best shown by FIGS. 2 and 3 from which it will be seen that in addition to a band-support wheel 8 which serves as a band-tensioning wheel 10, the bandtensioning device 11 includes a'support frame 12 fixedly positioned on the casting machine C and a rod assembly 14 having a lower plate 16 positioned on a mounting plate 13 of the support frame 12 and an upper plate 18 supported above the lower plate 16 by a plurality of parallel guide rods 19 and a shield member 90. There are three guide rods 19 with their ends fixed in apertures 20 in the lower plate 16 and in apertures 21 in the upper plate 18 by. set screws 22 that extend through the lower plate 16 and the upper plate 18.

Slideablycarried on the guide rods [[9 is a triangular support block 24 from which extends a wheel shaft 25 on which the band-tensioning wheel 10 is rotatably mounted by bearings 26. The guide rods 19 extend through passages 28 formed in center center line of the shaft'25 and the axis of rotation of the vIn addition ,toflthe passages 28, ;the support block 24 has a large central channel 30 which is closed at its upper end by a co'nnector'assernbly 31 that is attached to the support block 24 by boIts'IS. The connector assembly 31 includes a conical connector having a flange 34 by vwhich the connector assembly3l is latta'chedto the support block 24. A centrally located threaded aperture 35 extends through the connectorn ernber 32 at its apex and a connecting stud 36 is threadedly tioned in the aperture 35. The lower end of the connecting s formed into a socket 338 for a ballandsocket sen e and the upper end of the connecting stud 36 is formedat'39 to receive'an adjusting wrench (not shown).

A locking screw QDthr e'adedIy extends through the connector I support block 24. The center line of the guide sleeve 42 coincides with the center line CL of the central channel 30 and is substantially equidistant from all of the guide rods 19. As the supportblock'24and positioning plate 41 move along the guide rods 19, the guide sleeve slideably moves through a sleeve bearing SSpositio ied in anaperture 54 formed in both h 'l wI n .6. and f l ns p. 8 3- ardlyfextending tubular support housing 45 is m unt d h the q ni nepl ts v13 'b s m i I j K fW46ils mounted by bolts 70 at the lower end of the suppoit hdusijng 45 and has a drive shaft 51 which is driven by a motor 49'through a transmission v50.

The output shaft szof the jackscrew 46 extends up through the support housin and theaperture 54. At its upper end, the output-s 5 H jackscrew 4 6 is rotatably connected to a lower-th piate which is slideably movable within the guide sleeve 42; 58 is positioned in the guide sleeve 42 betweerithe lower thrust plate 56 and an upper thrii'st pla 1 and a conventional load cell 60 is positioned b5 h u pe hru P ats-5 Atitsuippei' and; the load cell 60 supports a connector block 61 which provides a cylindrical extension 62 and a socket "64 w' h the cylindrical extension 62. The lower end of the coup rigstud3 6iextends into the cylindrical extenl fa ball 6 3Jis r positioned within the sockets v now be understood that the output shaft 52 of the jackscrew the member, 5 8, and the load cell 60 provide a positioning ineansfor positioning the band-tensioning wheel Iii and the carrying m eans provided by the support block 24 along the center line CL of the central channel with a resili tforce'appliedthi'ough the single point provided by the ball 63 ithin the" sockets138'. and 68. It will also be understood he pring' 58 is a resilient means for providing the resilientf In addition itiv ll be understood that the position of the band teri sio wheel 10 defines the position of the support I i H e' position of the support block 24 and y s r i e to each other determine the compression" o f t he spring and-the magnitude of the resilient foree. Thus, maintaining the positions of the support block 24 and the lower thrust'plate 56 relative to each other substantially constant, memor e force with which the 'ban'd-tensioning wheel 10 is'urge'd against the band B'is maintained substantially constant with: thelresult that tension in the band B isrhaintairled substantially constant.

In thatembodiment of 'theiiivention disclosed herein, the load cell tillfthe jaek screw 46 and an appropriate circuit for making the jackscrew 46 responsive to theload cell 60 pro vide an -adjtusti ng means for maintaining the resilient force of thespring 58 substantially. constant by changing the position of thelower thrust plate 56, asthe spring'58 tends to be compressed or expended. by motion of thesupport block 24 in response to motionof the band-tensioningwheel 10 caused by operating conditions which tend to increase or decrease tension in the band B. This is because the initial increase or decrease in the resilient force which occurs when motion of the support block 24. causes a change in th the length of the spring 58 is sensed by the load cell 60 to provide an output in response to which the jackscrew 46 moves the lower thrust plate 56 to prevent a substantial change'in the position of the supportblock 24 relative to the lower thrust plate 56 In this connection, it will be understoodthat the load cell-60 is a conventional load cell which provides a first-output when the force applied at its ends by the upper thrust plate 59 and the connector block 61 is substantially greater than a predetermined value and a second'output-when this force is substantially less than the pr determined value-Moreover, it will also be understood the that the resilient force to which the load cell 60 is responsive is always along the center line of the guide sleeve 42 because the ball 63 in the sockets 38'and 64 provides a single point in this center line through which the band-tensioning wheel 10 and the band B are supported by the resilient force of thespring 58.

In addition, it will be understood that the single point is displaced beyond the axis of the band-tensioning wheel l0 in the direction of the resilient force of the spring 58 so that twisting spring 58 through the single point provided by the ball 63 so that the spring 58 isdirectly responsive toan increase in ten.- sion in the band B without the need for the increase in tension to overcome the inertia of support and other structure.

Finally, it will be understood the circuit by which the.

jackscrew 46 is made responsive to the load cell 60 maybe. any conventional circuit such as that shown in FIG. 4.

FIG. 4 schematically shows-a circuit by which the jackscrew 4 6 is made responsive to the output of the load cell 60. From FIG. 4, it will be seen that the load cell 60 is connected to the motor49 of the jackscrew 46 through a conventional motor controller 6650 that the motor 49 is operatively responsive to the load cell 6010 rotate the output shaft 52 and change the position of the. lower thrust plate 56. The controller, 66 is shown only as a block in FIG. 4 since it may be any one of many conventional devices or circuits which will be understood by those skilled in the art. I

In that embodiment of the invention disclosed herein, the circuit of FIG. 4 also includes an upper limiting switch ULS-l and a lower limiting switch LLS-l spaced along the discharge are opened when engaged by the actuator 71, The controller 66 is arranged in a conventional manner so that when the switch ULS-lis opernthe motor 49 is inoperative tomove the outputshaft 52 up, and when the switch LLS-l is open, the motor 49 is inoperative to move the output shaft 52 down.

In addition tobeingresponsiveto the load cell 60 and the switches ULS-l and LLS-l, the motor 49 is responsive to a manual switch MS-2 and a manual switch MS-3. A manual switch MS-2 is operated when it is desired to replace the band B. 'When the manual switch MS-2 is closed, jackscrew 46 operates and lowers the lower thrust plate 56. Another band is then placed in position and the manual switch MS-S is operated to raise the lower thrust plate56 and the band-tensioning wheel 10. After the band B is in position, the control circuit 66 again controls the position of the band-tensioning wheel in response to the output fromthe load cell 60. The load cell 60 then controls the motor 49 to maintain a constant predetermined tension in the bandB asdescribed above. The spring 58 allows compensation for abrupt changes in tension on the band B until the load cell 60 properly regulates the motor 49, and it will be understood that the resilient force of the spring 58 may be changed by changing the load cell 60 to a load cell having a different force to which it is responsive.

It will be obvious to those skilled in the art that many varia tions may be made in the embodiments chosen for the purpose of illustrating the present invention without departing from the scope thereof as defined by the appended claims.

We claim:

l. in a casting machine having a rotating casting wheel with a peripheral groove closed by a 'band, a band-tensioning device including a band-support wheel, a wheel-supporting means for urging said band-support wheel upwardly against said band with a tensioning force acting upwardly through a linearly movable single point.

2. The casting machine of claim 1 in which said wheel-sup porting means is resiliently responsive to motion of said bandsupport wheel and in which said wheel-supporting means includes adjusting means for maintainingsaid force substantially constant as said wheel-supporting means'responds to said motion of said band-support wheel. i i

3. The casting machine of claim 1 in which said wheel-supporting means includes a carrying means for carrying a shaft on which said band-support wheel is rotatably mounted for rotation about an axis, and a guiding means for guiding said carrying means along a line of motion transverse to said axis, said guiding means including a plurality of rods positioned parallel to said line of motion. t

4..The casting machine machine of claim 2 in which said wheel'supporting means includes a positioning means for positioning said carrying means along said line of motion with said force.

5. The casting machine of claim 4 in which said force is applied to said carrying means at said single point through a ball in a socket and said single point is displaced along said line of motion beyond said axis.

6. In a casting machine having a rotating casting wheel with a peripheral groove closed by a band, a band-tensioning device including a band-support wheel positioned to engage said band, a carrying means for carrying a shaft on which said band-support wheel is rotatably mounted, and a positioning means for positioning said carrying means along a line of motion in a position which urges said band-support wheel against said band with a tensioning forcefsaid positioning means including a load cell having a first end operatively connected to said carrying means and an opposite second end operatively output from said load cell.

7. The casting machine of claim 6 in which said resilient means is a spring and in which said force varies with the compression or expansion of said spring;

8. The casting machine of claim 7 in which said movable means is the output shaft of a jackscrew having a position which is selectively variable in response to each of a plurality of outputs from said load cell.

9, The casting machine of claim 8 in which at least one of said plurality of outputs from said load cell is in response to a force applied to said load cell between said first end and said second end which is greater than a predetermined force.

10. The casting machine of claim 8 including means independent of said plurality of outputs from said load cell for varying the position of said output shaft. 

